code: def test_grayscale(texture):
      grayscale = texture.to_grayscale()
      assert grayscale.n_components == 1
      assert grayscale.dimensions == texture.dimensions
  
      gray_again = grayscale.to_grayscale()
      assert gray_again == grayscale
      assert gray_again is not grayscale
  
imports: import numpy
  import pytest
  import vtk
  import pyvista
  from pyvista import examples
  from pyvista.core.errors import VTKVersionError
  from pyvista.plotting.texture import numpy_to_texture
label_desc: Use image node_id 16 for calling a global function with example usage: test_grayscale(texture) without return types